Pneumatic device for automatic die presses



March 17. 1925.

c. D. M DONALD PNEUMATIC DEVICE FOR AUTOMATIC DIE PRESSES Filed Dec.1'7, 192$ a wm, 4g 79 Patented Mar. 17, 1925.

UNITED STATES PATENT OFFICE.

PNEUMATIC DEVICE FOR AUTOMATIC DIE PRESSES.

- Application filed December 17, 1923. Serial No. 681,101.

To all whom it may concern:

Be it known that I, CHARLES D. MCDON- ALD, a citizen of the UnitedStates, and a resident of Chicago, Cook County, and State of Illinois,have invented certain new and useful Improvements in Pneumatic Devicesfor Automatic Die Presses, of which the following is declared to be afull, clear, and exact description. 7

The invention relates to pneumatic devices for die presses and itsprincipal object is to provide a pneumatic device operated by an elementof the die press mechanism, capable of creating a partial vacuum for thestrip lifters of the press and capable of supplying compressed air foruse in blowing away the stampings. It is well understood, that with manyautomatic die presses, the work (which usually comprises thin strips ofmetal) is lifted, one strip at a time, and inserted into the feed waywhere it is fed to the dies to be stamped up into articles. Usually thestrip lifters are 1n the form of vacuum devices and a vacuum-pump isemployed for providing the partial vacuum for the strip lifters. Thepump is usually operated by a driving member of the die press mechanism.In many cases when stamping metal articles with automatic die presses,especially when #the depth of the article is one half of an inch or moreit is necessary to blow the stamped pieces away from the dies afterbeing formed, to attain high speed and to avoid clipping such pieces onthe next down stroke of the punches. With the present invention thenecessary vacuum is maintained for lifting the metal strips, and airblasts are produced in timed relation to the strokes of the punches forblowing away the stamped pieces, thereby facilitating the work in highspeed die presses.

The invention consists in the several novel features hereinafter setforth and claimed. The invention is clearly illustrated in theaccompanying drawing, in which:

Fig. 1 is a side elevation of automatic die press mechanism, showing oneembodiment of the invention applied thereto; Fig. 2 is a detail, centralsection through the pneumatic cylinder; Fig. 3 is a detail, longitudinalsection through the vacuum chamber ofv the pneumatic cylinder, and'Fig.4 is a detail, vertical, longitudinal section through a fragmentoftheair nozzle. Referring to said drawing, which illustrates a simpleembodiment'of the invention press head 5, is a pneumatic cylinder 11,

closed by heads 12, 13 at its ends and con taining a piston 14. Thepiston is secured upon one end of a'piston rod 15 which is connected toan arm 16 bolted or otherwise secured to the pitman 7 The cylinder 11 isfulcrumed on its bracket, whereby it may oscillate thereon and the partsare so arranged that the rotary movement of the crank 8, is translatedinto reciprocatory movement of the piston rod and piston. The pistontravels from end to end of the cylinder, and at one side of the pistoncauses a partial vacuum for the strip lifters, and at the other sidecompresses air for delivering blasts of air to the dies. The end 17,forms the vacuum side of the cylinder and the end 18 forms thecompression side thereof. At the vacuum side 17 is a valve casing 19 inwhich is an air intake chamber 20 and an air discharge chamber 21separated by a partition 19. In the partition between the two chambersis a port 22 which is closed by an inwardly opening check valve 23, andleading out from the discharge chamber 21 is a discharge port 24 closedby an outwardly opening check valve 25. Threaded in the valve casing 19and opening to the intake chamber 20, is a pipe 26, to which isconnected a vacuum pipe 27 that leads to certain vacuum breakingmechanism 28 (operated by the die press mechanism) and from whichmechanism 28 a flexible vacuum pipe 29 leads to the strip lifters 30.The

construction and operation of the strip lifters is well understood andrequires no detailed description so far as this invention is concerned.

From the compression side 18 of the cylinder leads a compressed air pipe31, which is carried to a point adjacent the dies 6, at which placeanozzle 32 is secured to the compressed air pipe and is held in positionin front of the dies by a standard or other support 33 which may besecured to the press body. The discharge orifice of the nozzle 32isrestricted in size and is directed toward the dies as shown, andsupplies blasts of air which blow the stamped articles away from thedies.

In the operation of the device, the crank shaft 9 reciprocates thepunches 6 and also reciprocatesthe piston 14 through the instrumentalityof the bracket 16 and plston rod 15. The piston travels back and forthin the cylinder making one stroke for each revolution of the crankshaft. On its stroke in the direction of the arrow at, in Fig. 2, anyair contained in the vacuum end 17 of the cylinder is forced out throughthe port 24 and air is drawn into the compresslon end 18 of thecylinder. On the return stroke of the piston. the air in the end 17 ofthe cylinder is rarefied and a partial vacuum is produced in saidcylinder, the vacuum chamber, vacuum pipes 27, 29, and strip lifters 30,whereby the strips may be lifted by said strip lifters. Simultaneouslythe air contained in the compression end 18 of the cylinder is forcedthrough the com-.

pressed air pipe 31 and discharged through the discharge orifice of thenozzle 32, and the blast of air issuing from said nozzle is directedagainst the article which has been stamped out of the strip. In the formof the invention illustrated in the drawin the piston 14 is moved in thedirection 0 the arrow at, during-the last half of the down stroke of thecrank 8' and during the first half of the up stroke of the crank, duringwhich time air enters the compression side of the cylinder through thenozzle 32 and air pipe 31. During this portion of the down and upmovement of the punchthe latter punches the strip and moves upward andaway therefrom. During the last half of the up stroke of the crank 8 andfirst half of the down stroke of the crank the piston ltis moved towardthe compression end of the cylinder, thereby forcing the accumulated airout through the air pipe and nozzle, and because of the relativelynarrow discharge orifice of the nozzle the air is compressed in thecylinder and air pipe and issues from the nozzle in the form of a strongblast of air. This blast of air takes place while the punch is travelingupward and downward after having left the work ing is thereby blown awayfrom the dies, which makes it possible for the crank shaft to revolvewith comparatively high speed thereby greatly increasing the capacity ofthe press.

More or less variation of the exact detalls of construction is possiblewithout departing from the spirit of this invention I desire, therefore,not to limit myself to the exact form of the construction shown and andbefore it again reaches it. The stampdescribed, but intend, in thefollowing claims, to point out all of the invention disclosed herein.

I claim as new, and desire to secure by Letters Patent:

1. In a pneumatic device for the strip lifters and dies of die presses,a pneumatic cylinder, a piston traveling therein, plston actuatingmeans, a Vacuum chamber at one end of said cylinder, inlet and outletvalves therefor, a vacuum pipe leading from said vacuum chamber to thestrip lifters, and a compressed air pipe leading from the opposite endof the cylinder to the dies and having a nozzle directed towards saiddies.

2. In a pneumatic device for the strip lifters and dies of die presses,the combination with a press body, and a die actuating crank shaftjournaled thereon, of a pneumatic cylinder supported by said press body,a piston reciprocating in said cylinder, operative connections betweensaid piston and crank shaft, a vacuum chamber at one end of saidcylinder, inlet and outlet .valves therefor, a vacuum pipe leading fromsaid vacuum chamber to the strip lifters, and a compressed air pipeleadin from the other end of the cylinder to the %ies of the die pressand provided with a nozzle 'directed toward said dies.

3. In a pneumatic device for die presses,

ber to the strip lifter, and a compressed air pipe leading from theother end of the cylinder to a place adjacent the dies and having anozzle'directed towards said dies.

4. In a pneumatic device for die presses, the combination with a diepress body, a pneumatic strip" lifter, dies, a pitman, and

and arranged to actuate said pitman, of a pneumatic cylinder rocka'blymounted on said die press body, a piston reciprocating in said cylinder,a piston rod connected to said piston, an'arm connecting said piston rodto said pitman, a valve controlled vacuum chamber at one end of saidcylinder, a vacuum pipe leading from said vacuum chamber to the striplifter, and a compressed air pipe leading from the other end of thecylinder to a place adjacent the dies and having a nozzle directedtowards said dies.

CHARLES D. MoD ONALD.

a crank shaft journaled in said press body

